The present invention relates to a disk retaining mechanism in a disk drive of a type that retains a disk with a turntable and a clamper.
With the progress of compact-type personal computers and notebook-type personal computers, there is now a demand that disk drives installed in them need to be extremely thin. On the other hand, it is indispensable to increase speed of the devices and to improve recording and reproducing performance.
For this reason, the current disk drives generally employ a magnet-chucking method, in which a turntable for loading a disk and a clamper for retaining the disk in position are attracted by an attractive force of a magnet.
With regard to a centering mechanism of the clamper, it is now common to use a mechanism, in which one of the turntable and the clamper is provided with an engagement hole having a tapered surface, and the other with an engagement projection, so as to center the clamper with respect to the turntable by engaging them.
A disk retaining mechanism of the prior art will be described hereinafter using the accompanying drawings.
FIGS. 8A and 8B are side views depicting an essential part of the disk retaining mechanism of the prior art. FIG. 8A shows a state wherein a disk is clamped, and FIG. 8B a state of back-out. FIG. 9 is a sectional view of an essential part of the disk retaining mechanism of the prior art. FIG. 10 is a sectional view depicting a main part of the disk retaining mechanism of the prior art in a state of the centering engagement.
As shown in FIG. 9, a clamper unit comprises a disk holder 51, another disk holder 53 and a magnet 52 of an annular shape. The disk holder 53 has an engagement projection (m) formed in the center part of it. The clamper unit is retained by a clamper retaining member 59. The disk holders 51 and 53 are bonded together by adhesion or the like.
A turntable unit comprises a turntable 57 and a turntable yoke 56 of an annular shape. An engagement hole (f) is formed in the center of the turntable 57. The turntable unit rotates as it is connected to a motor unit 60 with a main shaft 58.
The clamper retaining member 59 is formed in such a shape that it retains an entire external periphery of the disk holder 51, as shown in FIG. 8A and FIG. 8B. The clamper unit is therefore retained reliably to prevent the clamper unit, including the disk holder 51, from becoming disengaged from the clamper retaining member 59. However, since the clamper unit is lifted obliquely by the clamper retaining member 59 when it is in the back-out position, as shown in FIG. 8B, it is indispensable for the clamper unit to maintain a back-out height (ht), thereby making it difficult to reduce thickness.
When a disk 63 is inserted, an electric signal activates a driving mechanism of the clamper retaining member 59, so as to thrust the disk holders 51 and 53 toward the turntable 57. As the disk holders 51 and 53 come close to the turntable 57, the engagement hole (f) in the turntable unit side and the engagement projection (m) on the clamper unit side come into contact, and subsequently engage with each other to achieve the centering. In addition, a magnetic circuit is formed between the magnet 52 and the turntable yoke 56, when the disk comes off the disk holder 51 due to an impact and the like, and damages the disk retaining mechanism.
However, it requires the magnet 52 to have the outer diameter larger than the inner diameter of the magnet retaining portion of the disk holder 51, thereby resulting in the magnet 52 of large size, and an increase in cost. In addition, the outer periphery of the magnet 52 is larger than that of the turntable yoke 56. Therefore, an effective magnetic circuit is not established in the peripheral area of the magnet yoke 52. Furthermore, there was also a problem that requires a large force to release an irregular clamping if the clamping occurs erroneously with no disk inserted therein, since the magnet 52 and the turntable yoke 56 make a close contact directly.
The present invention is intended to solve the above-described problem, and it aims at providing a disk retaining mechanism as well as a clamper for the disk retaining mechanism that achieve a reduction in thickness of a disk drive while maintaining good clamping force and centering accuracy at all times.
To solve the problem, the disk retaining mechanism of this invention comprises: a turntable unit for loading a disk; a motor unit for transferring rotation to the turntable unit; a clamper unit for holding the disk with the turntable unit; a clamper unit retaining member having a clamper unit retaining portion of a shape that a part of which an entire circumference is cut out, for retaining the clamper unit; and a guide unit disposed in a position closely confronting the clamper unit retaining member.
Further, a disk retaining mechanism of this invention comprises: a clamper unit having a depressing member for depressing the disk and a centering member disposed in generally a center of the disk depressing member; a turntable having a groove for engaging with the holders 51 and 53, and the turntable 57 come close to each other. As a result, the disk 63 is held between the disk holder 51 and the turntable 57 by an attractive force of the magnetism.
In this instance, the disk holder 51 and the disk holder 53 of the clamper unit are bonded into one-piece structure by adhesion, or the like, as shown in FIG. 9. This is effective in view of reducing the manufacturing cost. However, it is difficult to reduce the thickness, which is considered to be important, because it requires vertically a large space. Furthermore, because the engagement projection (m) is required to protrude downwardly below a bottom surface of the disk holder 51 due to its structure, it is necessary to take even a larger back-out height (ht).
Moreover, an engagement length (h3) is necessary for the main shaft 58 with respect to the turntable 57, as shown in FIG. 10, in order to ensure a certain coupling strength or greater in the engagement between the turntable 57 and the main shaft 58. Another engagement length (h1) is also indispensable between the engagement projection (m) and the engagement hole (f) to ensure the reliable centering. Furthermore, a clearance (h2) is also essential to gain a positive clamping force, even when there is dispersion in thickness of the disk 63 to be inserted. In short, a height of (h1+h2+h3) is at least necessary for the centering portion. For this reason, the vertical space became large, and it was difficult to reduce the thickness, an important matter. Moreover, the engagement projection (m) and the engagement hole (f) are generally equal in diameter to the main shaft 58 having a small diameter. Since the centering was carried out with the small diameter, it was difficult for the clamper to achieve a high centering accuracy.
As shown in FIG. 9, an outer diameter of the magnet 52 is designed to be larger than an inner diameter of a magnet retaining portion of the disk holder 51. This helps the attractive force produced by the magnet 52 to effect directly on the disk holder 51, so as to make possible a positive depression of the disk. It also prevents such an incident as the magnet 52 centering member; and a motor unit having a main shaft connected with the turntable, wherein a magnet is disposed on one of the disk depressing member and the turntable, and a ferromagnetic body on the other one in a position facing the magnet, so that the disk depressing member is attracted to the turntable unit by an attractive force of the magnet.
A clamper for the disk retaining mechanism of the present invention comprises: a turntable unit for loading a disk; a motor unit for transferring rotation to the turntable unit; and a clamper unit for holding the disk with the turntable unit, and the clamper unit comprises: a disk depressing member for depressing the disk; a magnet disposed within the disk depressing member; and a centering member disposed in generally a center of the disk depressing member, wherein the disk depressing member is attracted to the turntable unit by an attractive force of the magnet, thereby thrusting the centering member toward the turntable side.